The USS Erie (and her sister ship, the USS Charleston) were the largest gunboats built for the US Navy, similar in size to existing destroyers but slower and lacking a torpedo armament. Both entered service in 1936 and were designed to “fly the flag" overseas and equipped to function as flagships. The first cruise for the Erie was to Spain during the latter stages of its civil war to help evacuate US citizens still in the country. Later in the year it returned to its intended patrol area of the Atlantic side of Central and South America, especially around the Panama Canal Zone. At the start of WWII it was refurbished as a convoy escort and given heavier AA armament and basic anti-submarine weaponry. It was used to protect slow cargo ships. In December 1942, off the northern coast of Venezuela, it was torpedoed by a U-boat, with eleven men killed and eleven wounded. The Erie was beached and burned out, sinking after an attempt was made to tow it back to a shipyard for repairs.

Rather unusual for ships their size, they carried a seaplane for scouting purposes, although there was not room for a catapult so the plane had to be lowered into the water for takeoff. The plane was a Curtiss SOC Seagull initially but was replaced by a Vought Kingfisher (W:MP109) in 1942. A small Marine contingent was also carried (size is not specified, but was probably at least 16 men). It additionally had a ship's band, drawn from the crew.

The Erie carried a large number of small craft, including a 36' motor launch, a 35' motor boat, two 30' motor launches, two 26' whaleboats, a 10' punt and two balsa wood life rafts.

The four 6" Mark 17 guns are in single open mounts, two fore of the bridge and two aft of the funnel, which are rotated by two men at 2.5 degrees per second. The four 1.1" quad mounts (rotate at 6 degrees per second by one man) and four single 20mm mounts (rotate at 30 degrees per second by one man) and are spread out between the two middle 6" guns. Both depth charge racks are on the stern.

The crew is normally 180 men but can carry 243 (this included a Marine detachment and/or a staff for an admiral if operating as a flagship). The ship uses 312 gallons of fuel oil per hour at routine usage. At a speed of 14 mph, this gives a range of 9,200 miles.

Design Notes
The historical displacement of 2,339 tons was used to calculate performance data. Design draft was 12'; the historical number was used instead.

Original armament was four 6” guns and two quadruple 1.1” gun mounts.

The shield on the man guns only extend back partially; on a hit on the left, right or top, a 1d6 roll of 5-6 means the DR does not apply.

The luxury cabin is for an admiral, if one is carried.

Variants
The USS Charleston (PG-51) made her maiden cruise to various ports in the Mediterranean and spent a brief time along the Central American coast, before finally being sent to Alaska. It participated in the retaking of Attu Island in 1943, providing fire support to troops. It was attacked by Japanese aircraft but it took no hits from them and managed to down at least one plane. After the war, she made a trip to the Far East (including Hong Kong and Shanghai) before finally returning to the US in 1946. She was decommissioned in May but went on to serve as a training ship with the Massachusetts Maritime Academy until 1959.

Well... and why is a warship this big called a "patrol gunboat"? Official designation or what?

Official designation. When I was looking at other US gunboats of the same era, they ran from around 560 to 3,800 tons displacement. The Erie and Charleston were different in that they were purpose-built gunboats, not conversions of existing ships.

Nope, less than half that. The 9,200 miles at 14 mph is historical. I'm not sure where I found the tankage (or if I had to guesstimate it). I know that 780,000 gallons would put the design severely overweight.

Yeah, the cruising range doesn't actually mean on board fuel, since that doesn't jive with the "1,185 gallons of fuel oil per hour at routine usage" numbers you gave early.

It's a common issue on listed cruising ranges vs internal fuel, official numbers include in the range fuel from tankers accompanying the convoy, and/or refueling stops.

The Big Mo gets something like 4 yards to the gallon, and only carries 2.5M gallons of assorted fuel, yet its range is often listed as something like 17,250 miles (15k nm) at 17.25 mph (15 knots), instead of the 5,750 miles (5000 nm) it can actually make on internal tanks.

Well... and why is a warship this big called a "patrol gunboat"? Official designation or what?

It was also called a "peace cruiser" -- it was a "show the flag" and patrol the colonies type of vessel. IIRC the Washington and London treaties had a loophole allowing such a ship (relatively small & slow) to NOT count against the various cruiser/destroyer tonnage quotas. The idea was that since most of the signatory nations were empires (France, Italy, Japan, UK, even US -- see Philippines) they would want such ships and they'd be of limited use in war.

Actually, they might have been more useful as escorts against German "hilfskreuzer" types than were the various converted merchant ships.

As it was, again IIRC, the Erie/Charleston were the only US ships in this "peace cruiser" category. The French navy built a variety of "colonial sloops" for similar purposes, but I don't recall their characteristics off-hand.